SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a28bd0fd0d179d620834107f9383fe5dfeac458ad9c4373f6649be0fb12a8e71' 
  AND token = '97lSsPiGs5U8dFTLHZZ1CJ53Y1z1XBwJmdV0pmRMvuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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