SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2a3df7596d75cea567bdc059902122d67d15951904deff9ca6f99058f92afd5e' 
  AND token = 'n+KU3dOjGy01YCLATj7IKTu1gZQkNwa7byPhhqDTcBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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