SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bf1b39f3223f99d3111080491c3426ccc19f20d45ba973f438f6cc82abcaec46' 
  AND token = 'cZ9HYDtcaFEn8ESuV/C4xRAF+UtaOZ9fDbeKOrH6vEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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