SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7bb3a5d62db2362d40b4dbf149686ee32e421de0ce068d7a7dcf583891130cd5' 
  AND token = 'yTMsFxnYlciczWJZ9o1yxD0sCxrB0aQTRrwsQJJ+NWM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00069

JSON explain

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