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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '721109cbe5e380ff402f5f9af566029f6b7f1930d80e5aac3d9f6c2ad2c15fee' 
  AND token = 'Oi7ztMIuMJ5LV+AJ9oltzJsQTn6oChtBak3x4o+liQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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