SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'dff8fc391ca46d31c21f05151210d910b083251da2c026767308225bf9570b88' 
  AND token = 'mPXShPcUKyy+pLTBK05IK1Qnscv9qMJ6Upl7n9Q5CIE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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