SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '257f8c3e662c09542736ff1b09d44e1cb14d29e4bdb578d9c8f115d5e405c25a' 
  AND token = 'HSAzXeCtI89zpjksNaBRA+kBDeeJuxZnyJZUsq5uYIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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