SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31b99f737f38e54409859a8e2c2146180b1714ccf3006a8d2db049ca8ef850f2' 
  AND token = 'Z/+ocKyYM7Cu3z8V8StNUhp1Y3HqZqziHH/9y5GzK1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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