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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c856c3e1e03039137e1af380c4e14627ac8e40b726543d955321213e8f45ed44' 
  AND token = 'oIcUAre+wLSz7RkNBryTZzCw7WfP98B+lrWEuNoMyM0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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