SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc763ca9e6ab8fafc12d4c4fe432667e6dbfb1dbb4c8017595a538da848b9316' 
  AND token = 'aYv1XITqXfExkxdGSX9eNORfWyMVw9xPggk6fS1HB3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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