SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b888430b40f6d965b7830b2a485186d4fe6bcc5d8dcd9acafa84d8a7f1301f2e' 
  AND token = 'Dd9DzOcFVGg7mP6JEzl8dicSyVDo5uv/ywcUs8GMew4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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