SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86f57876e03de38f57106758cbaff93c9865b161b616bd05708a65a923a64be2' 
  AND token = 'BNUIZjHH9IkTxzvMjA6TcQ1/mHnElu9WHRswvQTGsws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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