SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c734b0623342895fdff7c4b6003691b90f8e9377bb96a7146c3aea1c04a1c030' 
  AND token = 'nkBrcQKAJeGlaZpIzCGZzGVoxyIbv+RuDQfgY2H4RFA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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