SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'dafc7202017f019a693815949f23f6d02b61df0db436288f72ea5d460aeda548' 
  AND token = 'Z8c+5SItpGoclelYjt9Wq8JlfxEo8jkqAblZu0gLn1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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