SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45ded121995d248c2f3d290ea257a2a4fc56d5adba18faa1bd19e1c5db755186' 
  AND token = 'IOTtNkTxT7SzjSasl7JUtXFvghrkjv0ubtgn/8NGNKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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