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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd8393c90d902e2076e9fe2fa81ed1fc5344bdd1dfa00e8a02455260091551c28' 
  AND token = 'J+LDoFix8kc9z6R6DdI1IHXrrj5/ZMg/3MrLPBKABLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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