SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c103e3f1d1e5f381e543ede53c1b35ce8c74aac40c0eec831f338b6d03b58a2a' 
  AND token = 'dRuB0f69y08j5kImYuPT9P5DiVH/UysxhzrFPF+aiSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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