SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3c62b47c17f36148337860247a2e533eb8c2e81953c57a2138385cab4612e16d' 
  AND token = 'vguszDBdKPFjBYDbgHZavTuR6r5YnmHv/GgN/ei3QE0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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