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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3a21f525f4625f189fdeb79f6edeb73b853cc8b61d971a766c9f48b44d5ea7b1' 
  AND token = 'Hm3LZymMmty83kLISslE1tU5AP6KzUEzIUO/lQYwh0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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