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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51d2a4cd62fefffce60c08365a72901e3beed463f1f9f1b4f447cbec8caafec3' 
  AND token = '9rg9EYr3dr76Vl/ll78k5Q7Ektg+X/tZDCG21I1FCB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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