SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0921ef6f92db34ff4cca0d3a744e9794eb739057dd870da2a91f87df4efd06e8' 
  AND token = 'UVt4rF+H6fxXUg29Ew2DYG7YUGnqM1k4Nu4h9Ai19MQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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