SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f87b8f71a99c6dd3dc4b438074135b16938156836bb144d3552c825fa8dcd918' 
  AND token = 'BEXDLqDFWmObCraaysd+kKYkQd9arehEzypg91/eJ7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}