SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8eacb1d4b036c73a0bfc27a6599d03a72407eebef16f0f9ee222633d8514830' 
  AND token = 'ApIxR7h8f6w0yHUhz61mEIv5pNgzWVuk0ccIIjjsh4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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