SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c50f76a0cd72de4d4a75e406d74bed7e549ac2dff2298803659d62aeecce641' 
  AND token = '8HesAbWW9r+p451oEYhUypcfotzNrZV2SKQrXd+mhEU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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