SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78f3006e9644af78d26837dec8bdd012086f662daea0345dca871afd255c16f0' 
  AND token = 'X25gSxKpkHiWzIYMPnJuNN7IvsMyfdyrSSptbPxUH4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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