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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '71a78cf8a61dd3696a9212117a4041041e6113e0b705a18c3ecbe88c3be84ff8' 
  AND token = 't63Z9fF0ICX+wrL3xtf9kfV+UtpxLxJi+lQX1YTz3Xk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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