SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b641045ddf7a2449ecad2a23e83bf2d9815fcd2bb7752710290b5cdb5adfd46' 
  AND token = '1EKk5yaudtqgv43JN+G/5rYh4SMFatQWpcek/AY74sU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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