SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46c47d4d240f10035666b46b44f31647549a306a96d2d13f6737761162af38cf' 
  AND token = 'P4tjwxTC7iiPFpQcnj/SWye0oSselLQTi3hWF8Pvzgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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