SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73c6ec21eb1dcd4641c8b5dbf049c8252944beedb094b78fc481c0b0e0317e96' 
  AND token = 'JfbBVnTPOABqBxk04ci5lBKvtY6HksMcgWLy2CQwIZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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