SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f0f729e3774d408dec0e0109ecf605e90285074790aa050f11db775b3e12a34' 
  AND token = 'cxksIkZBHGNre6XTkfaS6h56zVXGhhW1QdHSqVHotrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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