SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48d8ff193197a23f8399ec6e283649812d516c2547e118107f50d13f5184fede' 
  AND token = 'av8kHglkYf+BauO92qDrYM91OyEtxeTCzdlgOC3OkeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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