SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b557a9169f697bacc82945578ed141a5ef16d180f576fbfb5064a8034f75b080' 
  AND token = 'arFmupwK4SkEvcWKIleT2lG5q6VMRtwWSnKnd6MGd8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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