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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8fd79b35b1495c9b88fcf4cbb00f355d5155f1cf9babee8e442f9a5c52d1277e' 
  AND token = 'qH7XrWmQLTHq1WkIr8AJEUwMJNCex6uMMxQ9EEkN0iU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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