SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1c8794cc163ad16398a98df36246a7f2c420fff5268ce7bb4d5d79056347d03' 
  AND token = 'pGvd73K2VHBbQVqTkRHinX+YDKiYrBhv6p5PBSJtOts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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