SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16b5687f5c3fca967e3f2e55a1af86af468f643438850a9624779ee0be6abe14' 
  AND token = 'NaSk2nitrQtGoy/YFpFghaJrmzvGX96PMwJIsqq6/FY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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