SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27a0fcb5a50bc90e1894cb27a35d0f61c3deda047d08584112c75f64cac4166c' 
  AND token = 'ZxBAAUVmssy4EKw+kRuKEGFg1JwltNIqeL2kYmRTkhs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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