SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '608df8da57e7880e131ebe86dae9ec943ee706e75f4e713a58422cddeddd147e' 
  AND token = 'bvnpOZPutfn57osz2U1xl8OmvRuWJvs++nwa/ztfxY0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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