SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9947335af4bd31122576929943664ae9b51c2a0891f32c5e5f2cc281c77c44d' 
  AND token = 'GBY4xZ+SpesDl/mrUS4/vc8BbhZcIL90fh0VSVzVZ40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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