SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db5d050c54ee94d696b7982f1ea1b9806d94c56f93a898939877b9d5847f50a0' 
  AND token = 'jjMAhJ0nBG2QvaMSV9OwsspmPJlYnCXDgTswH6xvsyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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