SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aaad76b75ea221cce39cc41c9515539df720d26b585e0eb23ecf3efa134c1fa6' 
  AND token = 'EkhmWuwUt007DN4Q284TPamOVnThe3B1WgAGHvpvXDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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