SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdbc54ea026d8c34d22af7ded5b69da6d4b2115feb132038d1b9a92601676748' 
  AND token = 'sPxflrfgyq5MTYMt1cZVdTYFVvhbCjQ6CXHMktSCePg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}