SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16b30db6794a018799830298ca166b8163e4f70972b187ab05340001472985e8' 
  AND token = 'QBVC4XdsQIi9iVtPAIx+gDqCgAtTuJloHpfJUT/OEjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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