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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '63ba6d8bcf930ece160ad24fd506c370b1f157fb83bbb650a0e8ce7ab1a21789' 
  AND token = 'UaXstKKFATL3wYZdt1UEf4GUOigbaTD1UlH1lYwN9Rs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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