SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77ef213d60e24e9b32907c36ebcca70bab9260ed617311b0357cfb32c6d72467' 
  AND token = 'r8NwQDndqec9pLU8enR7I8HnsfSyGzP35CdeK39IEzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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