SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd4223fc7ec45317fcbe76c0b13aa997e29977bc5b39a0a3e1ea3c77453f870d' 
  AND token = 'mzAXMefSjF8ImaYugAyf/LWPqIQi+sXRTXab2Gybt0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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