SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '707632f9cb1c72d1271efc83055fd6b6f94bb7a3a8b1e8d0111dacc65cf57633' 
  AND token = '7cmKZDrY+2N58I48OgUN9dJQU/tq0attVP/rMIBBVGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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