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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2286c94e13a8775c030ef3c29f6f4f4bc4e2f7f7a22af46e21ee40b7afe78d93' 
  AND token = 'Y/BD//oMYzkSsr5aQe1eoc3QDDhtwzdfo+HGJJR8Qvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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