SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c6930903e4bf9e58fb1abea6df69d48aa530f38851eda0ff8501959d07d052' 
  AND token = '+Ur7LNeU3LJWWEPE/RlH8/RXYOEwvqgscmJvSYRnHhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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