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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '97a62b339b9d9c588e67010ea2faf187a9ec79f1e27599ea90dc56f8cca576ed' 
  AND token = 'muA7AdbNB9ql4wOeYSe8CFUo8V2tTnCRbIdxgRiWj7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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