SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fb88332489cf859aa9ff72d6e5f9eb7af67646471886c266c4e8bda55634e80' 
  AND token = 'URciKX1LtNfmRHLJuNYIVhff6lY2HtlB5xEzyIqGCZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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