SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ffa6c777ae84a0001cc5ff5cd49a1168edcee39273fa29b1793ede6559407546' 
  AND token = '8xqC15zOFb6cgt0brVSagAKB7JKM8xfb+Oay2kAn8Mk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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