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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b4b59f7c2cec83406f68fa103dd4cdc92a227e0ef24d90c38da07c46446a22e8' 
  AND token = 'TXOOPLizfnzQuK4ZWO9KvM/XpYABA6e1E5KNQZc3P6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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