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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6ffd1fb88ebdb2af3e97b7c00f26bdb5fac8fee6b339c623fd3dbcfa2b60edb5' 
  AND token = 'PYybGNQONnaFT4ZDFnBoR/TV0yot8nPVobByz4fMzh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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