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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc8cf47321ed2cccc884bab74fa5b16383d4bf8a9bc58ff6c8e90079a48e3b1e' 
  AND token = 'huSUzXUXpdrFrJC45UDHeVbOCbIsA31Z+uqEcDDAlhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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