SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '889fc0829317b80879c5998214246b3548d87dbd36df809d034b33ec96ccf59d' 
  AND token = '8XmKoUWy7tiJgWgYvMwiDk0qepevc52XfkVNmOIvxU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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