SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9c66306c23df51105e2d0f56d76450f8d04d9b2a9a31fc3062b85250f35b759' 
  AND token = 'pC1ATZqyu+r3wg4OHHVzWeeLyx2EsBM9RgCgIUYmK1A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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