SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff1623ff85727932c85ba02f518fe0868b3f15a40f92a206adffd4b25b30e0eb' 
  AND token = 'ciqNIdpHpq7A+AIUOsHMali21bskTK9n6XCyyf6imuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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