SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcca636842b072126d409306ed41d0948b625f8c319fe477a4c5f17d28998411' 
  AND token = 'l2jVvbZ9aZsujy+kjgFfJSHMun6BjZvBkMpCSJWK4vQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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