SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '175b005bcdccbb1aa0cf3d17e0500161540b76f3b8327bdcd83fa38879888ce7' 
  AND token = 'yAgUeeB72vSExrvN4lRzgbUIDFvOSqdSwytIpqmpAEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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