SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '931e475e8f236555b51d4f462f3e8bf3877bd857b6f943b5e2a182c4f40f152a' 
  AND token = 'a2nQnsnZsjtw8IaJQVYB13l6JrKOzqkgvb+Y9NISxrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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