SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fb2e62a03e69fc14694d7a48174f3060a9f771b8a013296cfc8762b2ef321c0' 
  AND token = 'lN6s3h5UQfGcG90CnI0SRkXaTzBGTpq9VxDxwaBuGMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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