SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac796da77033dabc0c931a21050d3b86fb0435b7c16b8cc303edeb381df0606d' 
  AND token = 'sdtnSUkt0e4wfaQQSOrSsLCVurbJrs32zdql9F4zkBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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