SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3b5237a399a60fc746412046fa4afe1a69a2f62ebc6c500fc21ebed2fd60a97f' 
  AND token = 'wncN520ths+L9FUacprrIsQMDvnvpyNI2AuZegdw1HI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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