SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f3696c414235ec603679a9997307a119b65a16ff59b2512fd4f580a11495982' 
  AND token = 'UKbG14Z/Pkj/OcdbRXCbp3fkogTzhtUkaqo+lJ/bB2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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