SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3519a9bba71d3770b90ba7cfa9655bf8f170de843f79b8d789e3006d0a39f7ec' 
  AND token = 'oCZW7+IbrX4WiaVpegPyJfYtay/tiHbRwVr0b3MdMGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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