SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb4f453d221be04f36844ca5e017cd298cb6a151649ecab16c1e81bfd4375748' 
  AND token = '9rfsezWRYXussZ5TPkGU7cqfydMrVkwRw9uDy+9VU0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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