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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a4cccd28a347943f7743ebc5c8b9138ceacc4194e649d28a0e7d20640a64cd2f' 
  AND token = 'MDc932QA/gjn3FQ2/+eDeYiKJDtP1Vxt8NBOi9ReulQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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