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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '20752bbb4a14ea310eb566920b33123364c3cc10b5a7e38c54065b763cdf8702' 
  AND token = 'vqnukExq4rnZnwJER3lPph0pgCfyTmMHvNhvTGNO8X8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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