SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14768a665ca33a8262defd5fa9003f734d497219befd31532cf52d8342a57196' 
  AND token = 'B/XM30epEmJSj013FCTjiTSiGnWaOtDjRAozdeSqdWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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