SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15f337e969001dd3d57b6a22d08f0cd66a2726a3f065d8491e1974b4682c0027' 
  AND token = '7LGaFvQQbYtaYJfKjs4XITUwpE2YjRx02oQRPOevzn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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