SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f876610a2de9a59e67c0cf4e6998b51a6b67005c14f65b8027cab80f6ea43e6c' 
  AND token = 'mseDZlJ/Q19UCguqBCtyZn80iBK+pqLwR/TnkY3R7ZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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