SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf5ddbdb3248a0d8e0b8dc736ea081bdfcf9a1f98c9520a75573c4a449e6f99c' 
  AND token = 'FgSRr8zjwgzAqLS8VvL6nfjVyOttfu4xUD/BM9UGFqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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