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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc6b27521a7e7b3ea1dd8c41d4866a5b58a47f73d893f40853ef54b20b9502f8' 
  AND token = 'Uquf7DHUgjgLM/mAa/ByHtcMraiilFN4sFqMxCZ+nNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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