SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '519ef9a70c0cbf2ff5d7f87016df9c720f41c2699d12f3f484465c986f64eab1' 
  AND token = 'GdERxCwEDbbGqb93Rz4goBtKhEx1zzLNQRF57OcNX8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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