SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9455ca7c6b9d415e788d01183318a8a26f01d53253aad836e5b1576e06d14e8' 
  AND token = 'cKjylbZYvccdYdGOBvUdnqgfICuFYzL7x1YA6Os+Hls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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