SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fe4250959feb181a31859248795e77fba83942dd97b3ebe5634fb74d4bd019d' 
  AND token = '6FZkL0Meyf3A3U4GDEfTjvTkkYkOxT0ypW97qPbJoH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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