SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9a4271a06942522b03ddaf1c77caeba6c82b2ddee7da3290c59bb2f7d1a1988' 
  AND token = 'Hwpm7FSijTPe9b4HZhK3QgfeDExT4HQgOQW8U5hC8lc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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