SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5637d18eb6bf7a3e3497468dbfc19b7030b18f43408889fb82ec874da7bd7bb' 
  AND token = 'PvtQgQz+wVqDfdhwNLRb7sln7yieXYtYIK6N4Ry5VF0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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