SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b61695de87dec3b7ab51035619e0fc874175a0ccb65e4125e680cb1b1ba3fbcb' 
  AND token = 'UBFXgXPzK+FBYcJxVPbcUT+rP11qniyDeAbEkoyRneY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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