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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '687831951a21f4364ba1e0b958371208d9fce23e1f5533581b558e3c8bf6c5a8' 
  AND token = 'ldfgOu1ltSfIvxFM8uNaX0yRQxdW6Azq35mOmAbjnFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}