SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4b3ca289544fb00d9d3c10840d2dda43d1fa354e3b72f595c1db45d1e5dbc7f' 
  AND token = '5RjpOmlN7Imu2aQtHVIHqknuyTs676UvVeDNHChcrss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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