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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8355a1c4b96fe8bad7a836d2d2e0dd7b7f10eaa4718fce8e78a3ba3de7998a80' 
  AND token = 'wXvgw7SOKDwpThFoIpFub7Ft2PMEUmOWTfRIOw2JojY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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