SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bf542c64b53c350c3d8616e453cddf4de79f253349bfbd6d839aa11c67e347f' 
  AND token = 'Z/uq3vQSNG2M8k8XHTZyUc+XZwFB1Vo5n2wGQ9ZuZiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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