SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f1fca0bd5bcfdc0fae3c9845791d6b6b957011b793535787910f9b85bbed6d6' 
  AND token = 'cSOMQF+HdvH9PpbeybYKX6YEFS5zMky6AjdfrTR9OxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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