SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f83d24900595d8f23c1700037ae9cc395ade935f693e992e0c14149fdcb5945d' 
  AND token = 'fuUhcyqYdrHsG959ycZy8SOwy981wjOJtExPjxlYgT0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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