SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f90baed97e718e1a3dad4477f565c35abd8d41e9ab13bb0eb5a252964b468b03' 
  AND token = 'Wg276YhAirZNFJGdZwyGeAoqlUdk+lbSVMQgpKqzNmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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