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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1b968aea22d3a11e147a1dd3ff64a8e2e9ee2f93dc576afac04bbbb43859244a' 
  AND token = 'vxyS7CMEQQBsh5JZc94+XO0zgWZgxk6aZb91Wy04WGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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