SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a87c4b9bc8161f9388ea639802fcf6b4844a64944fc1a8ffe99656b68b79318f' 
  AND token = 'tpJbqQXPAHqTtVcpGZjM+ddZAoay7SBPcHPOKKCNXvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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