SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'e5aba5400f05b9943462d68f3640fdbf0a4fe58b2ab71624e246b06369bb11d6' 
  AND token = 'a/n5VB4hhLHYgMpbG2AdFPfwo9Jj+vOY3EfS7JkeV2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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