SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8af235cb08da4b294f0a53071baf50400ddd4bd7f89fdf929855054b681f99bf' 
  AND token = 'R+c/htJzXn1HxfGbyx3SN6WEWb4zS3ZRTitoWgdaS6w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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