SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bb1fb6a25a6347ba8822ab51788ce581af3bf2f1669b8883cc78005b8114743' 
  AND token = 'DO2cHS0UZWZKYdy8sHZ4clIF7F7RgAvcnpL945bhzAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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