SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b96b20c85b28b5d1dbafbc516d739cdec27b69da9135426632af98fdbd0fb0b4' 
  AND token = 'dX1ybX7xh327i/t2pZh9qU6vIOF1wULMixDWtgMBJBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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