SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b98aaa33a55798f61a6764489a60d092af317800b6bd3deee196e63efe377437' 
  AND token = 'OM1ltGSF9c1tBtPlnoBzQhHkIDTW4BAsfdkfJYZGqOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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