SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3a76f8130b5d7ef8e2632b3f01d135a1f844e7777deffcdcce544f40326ed28' 
  AND token = 'jBzDQsbOUlEFnsq3v/LuiAoFUtOvzm/PrlBs+39Zeh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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