SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b4239e010f2bde85c4d8a40fcd80035524434fcc0703dc3cfb9c92bcc81da23' 
  AND token = 'uPgebHkMhsds0kgQb2kqZ4JGcGkVAPg5+XxC3YOgs9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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