SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b3ea0846748d62600eb997802a4305ff9a7d1c9aa923165797c283921c35914' 
  AND token = 'dDFHr6fjgI00m/Jv+8EYKlS/TkJabJ5LwpjDWywZVWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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