SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20790edbbe2880b08b509155617e38e7cefe6fc16a666bc938e5cbf9982b568c' 
  AND token = 'BTCbY4DDLPMbl1/eKELETpyCahrQx1AasBZ4JpsIcm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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