SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34dcbd6b7e936b355a2080ef23262bf73aa59e98b60d74e397e8ede190f6b83f' 
  AND token = 'sYz4qEl4/bhG8KwDZjNwjTEH4eByE6mHg5zWfHZzvo0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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