SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4284e4b77891707de240a07a04476c56d71642405d7d16c13b1b8cb62987c9a5' 
  AND token = 'icAXUxu6JLrIwnaKBYH+VemMwEYAFGtAipHoNOmeCpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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