SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd956da2379197a9cbfecb8f280e25c24b4046a4fe0d420fbc9d793ee92453021' 
  AND token = 'TusZqgVoktKRxFjiMAXtwAlixHipnkD8LYT9H4KoJzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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