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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d52c817cab799df085d768fe6add1d902075691b8f66913084b8d63f80c5342' 
  AND token = '9cWMb2ER0j374okVKWKTR+XAdnFvUaWJcES2skxghV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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