SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0c37a49168bde54519556295f7b8bd81631b810a148a1aa66976d105045e95c' 
  AND token = 'fhmRTFaKZLt7jWdptB77RIxedLc1i/25MdEVUCBHjjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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