SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3d87bbfdd5d4c355fa003e63172e6188f7fca2b3e319c646f4b45a5b5ddd8d7' 
  AND token = 'ew67EYHDpchhzCJ6m/47jydvnOLLEZRfZ3g9r9NYxvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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