SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21a8bab82b6cd6afcfe0172e617cf6f222222444a388045ed7fb765d978e4648' 
  AND token = 'ewl8aPFQIP6kEd0OZtjWP3mKinERmqzkaahielkCAKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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