SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f256db3be9f312385f0ce685b24c41ce88be41698f4cff00569e72007c5ad167' 
  AND token = 'SqCUbzeW7nDcVUVPXjo3APHCazNZ9xiYkTv/SDBJzN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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