SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91e9f38f77ad5554b9c603c11748e63c6e95deab189b58d0d15c187b7d60ff33' 
  AND token = '/D4UvmoPO8FJyUQaLFqERHDKur/ZnwWn0po1ugvTTzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}