SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83a626ac758af0341a4fbfba9509c1c84315b215db2aa5a1573620867f68e763' 
  AND token = 'e/6KqAF8CAHLQZgNtZcO+sNxioqlBJFnEZO8R1uH/Wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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