SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a75fa96613a6b3a20438d37b37eda2cc966ef8c8afde8bea33e12498583b95b' 
  AND token = 'dsdCKHAkIlK9ZhIxJaTD5pMK/nkgDfJ9xCPCLibMkj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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