SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fefe234512cf901dd33f04c2d9a3395a0a74f99541533e1e83bf8bd29793e57c' 
  AND token = 'wB99ed4KAwadaLXfcKwIJa0Ttzbi/4JNo6bl21ATQOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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