SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f29a4d133d7e67be2d6e70dc0af31fa9087ec245d18251ba1d20fdb087df0d2' 
  AND token = 'H3FpFNBnHTuMNB1TtW39AC9YqaCyse/dlzGxmQpENTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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