SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '577a1000e4bfc87b3c57e4350edadb3844bb4b9db693037afdc284de6e5e06a4' 
  AND token = '52mSrCbOhWZQYvYmGO6BpTOGK24BO56/WUUW4a569OM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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