SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efa57f888393c9d98b145912a751ea3fb76820a1a8f7e3d023ca85542acb10ab' 
  AND token = 'BakjVmyKZ1Fz5q38oxolvYQ7FD2hFqPtbKXlP3+DyWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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