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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70f743103adc49bef7258abb3fbbd6235837e7a00f4760707165d9f9ad41f8f6' 
  AND token = 'blbTsTaz+b9VrJl0URocDiGmzMUd0CqPWY9+CCuDQPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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