SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '258bf8cb10faa9d1c4a3f0c8e65ef120c8aa966b7aee231479f7721cacc0bf59' 
  AND token = '5GlB8RVs5nA8w4EjzEPkpmFuvD7PHAjcuU+Ld/ChdGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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