SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6297d3e17385b38693d95f55896960f92140668187b895dcf56d848f70d8d40' 
  AND token = 'HVZ755WSSnzDyAbyrg1NFeEUnyZonL1IPLqLYnPy21o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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