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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4c356635d9695921a7f1ef41b782818de9c77ff0800b891ad418e51922a9fe4' 
  AND token = 'lTaTx9JZcz1M9ZBrOCpmWr7MdtU8cIEc4aVy+XeORrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}