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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71f09bc497bd72a00af5d6dfc9cecfa7428601b9a1c40d27ff0e6c5b2e096e21' 
  AND token = 'py+jZIfV7bZHIRW4tU4cbaS3wZAtZQGCbpZDpAAN5Q4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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