SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6e15c2aabb33b54943c90d7b4a15320a9722636cbdf8fae71271cef829a486e' 
  AND token = 'nTAODhj2XFTLUyEblrbR5ijVqXdOzurnYqF7JQ4YG2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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