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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3e9c6d1b220394a5754bc9536a4e02ec6d1c8f9d0bded35b150b0b3ff277c0a5' 
  AND token = 'X3Az9issBf1trWatrpzbvJhK5d4FV9Q99yNR6JL9oVc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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