SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c1e9a274bc46d66c2d10c41ff877f974334f4bb83a7b748bdfa08cc06890ca6' 
  AND token = 'jKjM4fgWnz1u7toBqUhAuZ4aJZ+v8B6lZD2Xau7nNYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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