SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6b87de4813df2ead41cf7291655022363a9da63ec8bd62db635123916df5c08' 
  AND token = 'sPHVLsBvbM8UwDZ1gpIC1/qSBKRdAYphZqwNhC8OGe0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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