SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75415dee9a42b92e3c67673ffee6c604b1b96369a6bd5b02ca724f342f854abd' 
  AND token = '5HxVvRgE1gzNlxrhtIO+r1GReQQzAZDY2NPzV/hudjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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