SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '315f48693f0a5bc47cc8a88bd780383e894699737d482d5abe9a3f92066e227b' 
  AND token = 'GvVXReAa07uaye5IrOVXV7gKCbUqhROrG136ZMUMPWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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