SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9a1ff81013fda75e8d59b8fa478012ae360c266d31591f6babdf079be93df54' 
  AND token = 'DF9tkwp4JqFrctBowCLYMmu+q/O0dlZnEs7gT2M8cyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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