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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfa3ed9bda847499924670cf09995ac0d4ca4dac1fd2574bb6e58bc4412a6c8f' 
  AND token = '4h/NQ0lAp5hmGtDeKktKJ+s7Bsi8jDQIajhxkEoMLdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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