SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3b6698f84fa5a18ad267f502a1252d32db7f9ba33dcbf329f390717bba43331' 
  AND token = 'UZMYPPjHvd+HrJvLW/Zdhkl0xOrUDfEwn+LNvTx6EgU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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