SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84ec9a75574b1441a8ecc2fd8b76148a2f7e36839e6c158d99366949dff2c37d' 
  AND token = 'pj1WKO/JAR0e/f0nzNAD5sIVpWPDwdqSyALzg+Sv+bY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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