SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d51b5276b45d4c61fbf317a9fd42d1c08184e2e5d38b8815b27b55242ff084e' 
  AND token = 'z+TckhsHuiLEqzIm6mgo4fvRwBhjQrfx+YOojYTN7rQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

JSON explain

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