SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac541d718d10e3b5419faeb73e42bfb3ff17ce12870959c97ad1db15be4fdddf' 
  AND token = 'fKMUyQwh1IBNNkKNK2jB1k323MCWqvFcogz1tgywWUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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