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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6fc2ad55797d960aa9f16dffce28e143322963c483ec01052647df17a5c0c75' 
  AND token = '/8wfOzVYR2QKOAy5qPoklhMnEoViyunByk03hHeAQO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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