SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21247f3b74ba2da6364daddf70988f6eadd089e45a7d5701568a35d40db41869' 
  AND token = 'vBtWfF2Y3LhW7GOk+tJ+SC6z1q4U6hz+XkvdyMunml8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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