SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '902560bdc33914341eb20119b4ac532e46a49233c9ded249e4ef973de5701e00' 
  AND token = 'yhKpxHfvBVJQHrrXASEmZD+3ye56WEaf0aYQAjAPZNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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