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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f3d3759c2ec426e3e4b6e694e441a0f541dc5a35a73e2f76934bbfa0a305996' 
  AND token = 'Ok7+YzjYEk+L5Lqve1dgPsyD9vkatFLR1QWmUC2OaB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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