SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef54727b41a2911461e512fe46b98e122706027d85aecb3467d09e530c858393' 
  AND token = '+ZZrPhWsrEYajUdHHS1x8QPHZHvoR7yIUSC+IMxiMDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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