SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e5942d099668e01c2358ae16092799f370a23cb24f52933af329e50aab2ce23' 
  AND token = '3alr7n+NMYV0wxjk3FV+re66HmdGD+awHwjo7sZ+0Dg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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