SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '491633e37e706273e44944d5c1f04478c02c63093eb8e48c46223db964b13813' 
  AND token = 'tjWyWq/E1Wndc62xL4PTyEe/N9QCDvjUPnRFhaln/K4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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