SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8588e2ed8d926d862a1516ba61221d0bb6de8422622403ff4f0cae7beff3c39d' 
  AND token = 'SRRTUtyxKfpj/UfR9rarmg79oOtU2aD61WSYVRBoYSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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