SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b52c6283915e36c80424dbffa3a544911999c8dc97b370a5aec020db739e0fc' 
  AND token = 'MjmWpJHnVVRIL50bVHhRXgbQ0wmx2bYnYnnmQZFzzIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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