SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '994bfbc81e8abe61f5ca6467ad7f85f37543e87495ec3a6aea99bcb556f4e052' 
  AND token = '23K9/9WDr0BZsEItoROdIfXnTTrg6y3kHXaeQrtPtZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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