SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf00da064ea911937d4c1b1ec54207de0d8c55fce4e4c8bfd9e085ff02657897' 
  AND token = 'FxtgGDLMHAV9URmHlF5Nq6ahMHIcaXtn8K8Teb5K9Wk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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