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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '976412e8145a9c931ed5b52d187ee3fef80935307a3d6bfc1a7e6c6ada857f83' 
  AND token = 'EWiG16C65Iuojk9nkLwiClnQ5GlZxSTWUlkE1fpTeHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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