SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b623901eac164aecd3579c34e1fd84f767d98ddf2f0ee91d9af472c1caf7de8d' 
  AND token = 'HEmORZn/wgOu/guSXwhFWTkYkXIwAU328xBm17qucIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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