SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af34e5ac997102e868504985f04a444721a2c0a09dbfbf09d4d31d13efc7ad7a' 
  AND token = 'bX6Ehm3vZqhhJkunydypGxVXaSzE9GGI+qIQlnXkNJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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