SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '11a38efc9cbba83c738a911273f80058213fb5f944a1f0acec2d1c87c1ce6421' 
  AND token = 'KaUHjdd9c7tFegEiLOwNhvzIPwgG0Hk67CnQMyQZGc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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