SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '567545f864854a1acc9da29e83dc0453ce1116538206563bc964b40eb9234232' 
  AND token = 'OxKDH/u0EkdOiTMPveWLrAXsapKQYc1H1Ggqq41JkEw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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