SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '504d5ef418efdbeba8cf8416b595c93f43f2f0bf43983f296a832826a34a52e0' 
  AND token = 'SWNSidE7wl1F1aPeeGwhr6ifSMZiNwQXbWZ1mFjnkAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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