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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3ecaf5c661d86680c6ad2c08552fa5afba78adb6c096c27a97bb4eb2d52fe3cc' 
  AND token = '3oA6VxLzfehN4ZkRYae0Us4QBKSttkN5AFxEy+3Eesw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}