SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '850e8a8ffe571bd37661d7a419c315007f3e0e0828f9ced1da7e7be9c48c008b' 
  AND token = '8ywwfs56zkkNnrK/pobh55M1SgvFwIFZ9u0rv9rXUQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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