SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '299ef4924677e38da27e87339f55aa53d28e63fc93201d7a94f2870ddc544f44' 
  AND token = 'WJIVjgvh1j6uVBxyvLSxw2Esu6AvtjM3JzsgZatGPgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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