SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c7c8e650b0cd57141ce636c7939c54760277ec9e97355e5ca18c9a78addff27' 
  AND token = 'p7RkE7AyXdJqUWBpCjcZZhgMiPameKGZ/lsNrDaSi+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}